The present invention relates to a control system for a supercharger in an internal combustion engine, and more particularly to a control system for controlling a motor/generator mounted on the turbine shaft of a supercharger when the motor/generator is used as a motor or a generator.
Motor vehicles powered by internal combustion engines are equipped with many electrical devices such as a starter motor, an ignition device, an alarm buzzer device, various illumination devices including headlights, and indicators. These electrical devices are powered by a secondary cell in the form of a battery, which can be charged by a generator mounted on the motor vehicle and driven by the internal combustion engine. New additional electrical devices are being developed nowadays for use on the motor vehicles, and hence the electric power consumption on the motor vehicles is being increased.
To meet the increased electric power demand, the electric power generated by the generator driven by the output of the internal combustion engine is employed to charge the battery. The electric energy thus generated is converted from mechanical rotational energy which is applied from the crankshaft of the internal combustion engine through a V belt to the generator. Therefore, part of the net output from the internal combustion engine is consumed as electric power by electrical devices. With this arrangement, thus, the internal combustion engine is subject to a load.
The external shape or dimensions of the generator are limited by the layout of the internal combustion engine, and the maximum electric power generated by the generator is about 700 W-24 V, for example. Such a limited amount of electric power available may not be able to meet the total amount of electric power consumption which is expected to be increased in the future.
Japanese Patent Application No. 59(1984)-51559 discloses a turbocharger associated with an internal combustion engine. The turbocharger includes a turbine driven by the energy of an exhaust gas emitted from the engine, and a compressor operated by the turbine for charging air into the engine cylinders for efficiently burning fuel therein. When the internal combustion engine operates at a low speed, however, the pressure of charged air is low since the exhaust gas energy is small, resulting in low charging efficiency, and the output power and torque of the engine are not sufficient.